My vehicle is a quad-cab 2000 Dodge Dakota 4.7L V8, 4x4. It has nearly 220k miles on it. On occasion when starting the engine when the engine is already warm cylinder 2 will misfire for a while, a check engine light comes up with an OBD code of P0202 (cylinder 2 injector circuit malfunction), and eventually goes away after driving down the road a bit. It doesn't do it every time, either.

I took a resistance reading with a multimeter of that fuel injector and got 15.7***937;. But, the service manual for my truck says the resistance of the fuel injectors should be 12***937; with a tolerance of 1.2***937; (10%). I also checked the resistance of a few other fuel injectors. Cylinder 8 injector is at 17.5***937;, cylinder 6 injector is at 14***937;, and cylinder 1 injector is at 19.2***937;.

Last year I got a couple OBD codes randomly for the injector circuit malfunction on cylinder 1 and 8. I'm thinking that most, if not all of these injectors are out of spec and should probably be replaced soon. The other cylinders are harder to check the resistances on since they're a bit buried under stuff.

Here is my question. Would it be wise for me to replace all the injectors at one time? They look pretty old and are most likely stock. It wouldn't surprise me if they have some deposit buildup as well which may contribute to the resistance problem. While the misfires are rare, I can eventually reproduce it with frequent stopping and starting of the engine while it is warm. I'm thinking if I replace them all now, even though it's more expensive in the short term, it's less work in the future.

It's generally better just to rip them all out and put all new ones in. With a vehicle that old, buildup is likely becoming a problem for several of them. The misfire in your #2 doesn't necessarily have to be from buildup either, it could just be the injector is malfunctioning due to age and wear. Just replace them all. Saves you on labor costs (or time costs if you do it yourself).

Personally I'd buy 8 new ones off ebay for $80-$150 and change them all. Even if you spend the time to clean them you would still need the flow rates checked in case you have a bad tip on one.

If you do get the new ones, just get the same size. No need to spend the money for bigger injectors, you won't see any gain off a stock tune and fuel pump. Will probably get worse mpg also.

If you have to pull a fuel rail, might as well change them all, make sure they all come with new O rings too. Be easy with the fuel rail bolts, take your time and spray them if you get any resistance taking them out.

Generally, replacing a single injector isn't an issue. Given the age/mileage though, you're better off replacing all of them.

I recommend Vaseline for installing injectors...works quite well.

Before replacing injectors....try my little trick. Pickup a bottle of Safeguard Ethanol fuel conditioner and stabilizer from your local parts store. I recommend the 16oz bottle. Add to gas tank in accordance with the label (or as close as you can, a little extra won't hurt anything though). Burn the entire tank prior to refilling. See if the condition continues.

Generally, replacing a single injector isn't an issue. Given the age/mileage though, you're better off replacing all of them.

I recommend Vaseline for installing injectors...works quite well.

Before replacing injectors....try my little trick. Pickup a bottle of Safeguard Ethanol fuel conditioner and stabilizer from your local parts store. I recommend the 16oz bottle. Add to gas tank in accordance with the label (or as close as you can, a little extra won't hurt anything though). Burn the entire tank prior to refilling. See if the condition continues.

This stuff stopped my Check Engine issues. I was getting P0161 and P0158 codes every other day starting at the end of Winter. Started adding this to my tank for the last 4 fill-ups and no more Check Engine codes. The first tank fill I had one Check Engine light but the last 3 fill-ups I've had none and my fuel economy has improved to boot by at least 3MPG

(P0161 and P0158 on a 1997 Suburban is a issue with the Bank 2 O2 Censor behind the Cat on the passenger side.)

Don't bother cleaning your injectors with crap you dump into your gas tank. Use stuff that you hook directly into your fuel-rail. You will probably want to have a shop do it, since the kit can be a bit pricey.

With over 200,000 miles on a gas engine, it may just be a good idea to replace all of the injectors, especially since most of them seem to be wearing out.

I pulled them out and cleaned them. I also moved that suspect injector to a different cylinder to make sure it's that injector causing the problem. If it happens again I'll replace them. Oreilly Auto Parts has BWD fuel injectors for $63 each.

@The Fool - cleaning by hand is great for getting the exterior of the tip clean but does nothing for getting the buildup (if any) inside the injectors out.

Quote:

Originally Posted by erocker

Don't bother cleaning your injectors with crap you dump into your gas tank. Use stuff that you hook directly into your fuel-rail. You will probably want to have a shop do it, since the kit can be a bit pricey.

With over 200,000 miles on a gas engine, it may just be a good idea to replace all of the injectors, especially since most of them seem to be wearing out.

The crap requiring a contraption that hooks directly into the fuel rail can damage injectors. It can also damage catalytic converters. Most injectors come with a Teflon coating. The fuel injector cleaners that are introduced through the fuel rail have a tendency to remove that coating, resulting in more problems later. Those chemicals also cause the catalytic converters to heat up more than they're designed to, which can result in damage.

The chemical I recommended, I know for a fact works as advertised when used as directed. I don't recommend chemicals I haven't personally tested and verified the effectiveness and safety of.

Quote:

Originally Posted by IcE

Yeah, gas tank added fuel system cleaners don't do a damn thing in my experience. But what you've done is acceptable, since you cleaned them by hand.

I have 2 scooters, a lawnmower and a car sitting here, that say you're wrong....

@The Fool - cleaning by hand is great for getting the exterior of the tip clean but does nothing for getting the buildup (if any) inside the injectors out.

The crap requiring a contraption that hooks directly into the fuel rail can damage injectors. It can also damage catalytic converters. Most injectors come with a Teflon coating. The fuel injector cleaners that are introduced through the fuel rail have a tendency to remove that coating, resulting in more problems later. Those chemicals also cause the catalytic converters to heat up more than they're designed to, which can result in damage.

The chemical I recommended, I know for a fact works as advertised when used as directed. I don't recommend chemicals I haven't personally tested and verified the effectiveness and safety of.

I have 2 scooters, a lawnmower and a car sitting here, that say you're wrong....

And I have two cars that say I'm right, what's your point? I said "in my experience" for a reason. Injectors tend to fail around the same time buildup becomes an actual problem, so you're just prolonging the inevitable (or doing nothing) when you use stuff like that. Also, carbon residue buildup primarily appears around the tip. Internal should be negligible.

Well, after moving that injector it still acted up in the different cylinder. Even if cleaning things didn't help, now I know for certain it's an injector issue. I'll buy eight new injectors tomorrow and install them.

I'll tell you what, I'd much rather work on computer hardware all day instead of engines.

And I have two cars that say I'm right, what's your point? I said "in my experience" for a reason. Injectors tend to fail around the same time buildup becomes an actual problem, so you're just prolonging the inevitable (or doing nothing) when you use stuff like that. Also, carbon residue buildup primarily appears around the tip. Internal should be negligible.

If you had said "most", then you'd be right. In total I've found 2, out of the dozen gas treatments that I've tested, that actually work. Lucas Oil's Safeguard Ethanol Fuel Conditioner and Chevron's Fuel System cleaner with Techron.

Internal is not negligible. Most "fuel injector cleaners" remove the Teflon coating that's found inside fuel injectors. That Teflon coating serves 3 purposes. It provides an internal lubricant for the injector, an anti-corrosion coating as well as preventing particle buildup on the nozzle. Chevron's Techron additive actually supplements the Teflon coating while removing corrosion buildup inside the injectors.

Basically, if you don't have a problem...benefits from using such fuel system cleaners won't be noticeable.

I have personally tested both on several dozens of vehicles and know for a fact that they both work. I didn't just pour them into my own vehicles and start making claims without understanding exactly how they work and what it is that they do. I have actually seen first hand what they can do when used properly. I've even seen the effects of the fuel injector cleaners that erocker suggested and can tell you that none of the auto makers actually support the use of such cleaners stating that they can cause premature injector failure as well as premature failure of catalytic converters (for cars that have them, obviously). I've even replaced injectors and catalytic converters as a result of such cleaners.

Before changing over your injectors with new ones, fill up, put in a polyetheramine based fuel cleaner, drive it down until you are low on fuel (not so it runs out, that would be bad!), then replace the injectors (before refueling). You will also want to change the fuel filter at the same time. The reason why you do this is to remove any loose gunk in the fuel lines and fuel tank, so you don't accidentally clog the new injectors.

I decided that I will clean them first. If they cause an issue again in the near future then I will replace them.

Cleaning does nothing for the electro-magnetic coil that actuates the pin valve in the injectors if the resistance is out of spec there are two possible problems out of spec injector or the battery in your ohm meter may be dying ( trust me that will cause some odd readings).

Before changing over your injectors with new ones, fill up, put in a polyetheramine based fuel cleaner, drive it down until you are low on fuel (not so it runs out, that would be bad!), then replace the injectors (before refueling). You will also want to change the fuel filter at the same time. The reason why you do this is to remove any loose gunk in the fuel lines and fuel tank, so you don't accidentally clog the new injectors.

Very logical. Sadly, not all polyetheramine based fuel system cleaners are created equal. Chevron is the master though as it's something they developed.

Btw, never trust the marketing images found on such products. If the pictures were accurate representations of the before and after, the results would be as noticeable as the difference between a 3cylinder Geo Metro and a Corvette....

True, but the main purpose of the recommendation wasn't to miraculously re-perfect the spray pattern, it was to dissolve the gunk in the fuel line so it won't potentially clog the new injectors (whether it is now or in 6 months time).

Before changing over your injectors with new ones, fill up, put in a polyetheramine based fuel cleaner, drive it down until you are low on fuel (not so it runs out, that would be bad!), then replace the injectors (before refueling). You will also want to change the fuel filter at the same time. The reason why you do this is to remove any loose gunk in the fuel lines and fuel tank, so you don't accidentally clog the new injectors.

As I was looking up the procedure for changing the fuel filter I saw this:
To me that says not to replace the fuel filter unless it's the cause of a problem.

Also, I doubt the multimeter is measuring incorrectly. It has a new battery and I haven't had it long.

Didn't realise that for your car the fuel filter and fuel regulator are a single unit (by all engines it means all engines for your vehicle model).

Having a combined thing like that probably makes it cheaper to manufacture, but makes it more expensive to replace. Also, by the looks of it, you have to wait for the filter to become clogged before you replace it, which is less than ideal! Typically the fuel regulator never needs replacing, so having them combined also means you are replacing a perfectly good part just for a new filter which are quite cheap.

An inline fuel filter doesn't need to be replaced any sooner than one of those combined units, it's just preventative maintenance. If you look at a traditional fuel filter it seems to have a larger filtering capacity than the combined one you have. It's possible the injectors are stuffed due to ineffective filtering... Fuel injectors require very pure fuel (in terms of absolutely no solids) due to the action of the internal valve and nozzles, I doubt such a small filter on the regulator will provide the 100 percent filtering required to prevent fuel injector damage. This would probably show up in the resistance due to the solenoid action.

I haven't heard of fuel injectors themselves actually becoming faulty, only the nozzles becoming a little clogged due to carbon deposits from the actual chamber, which is what is represented on fuel system cleaner boxes. Of course, I haven't heard of companies cheapening out to the extent of a combined fuel filter/fuel regulator before either.

Didn't realise that for your car the fuel filter and fuel regulator are a single unit (by all engines it means all engines for your vehicle model).

Having a combined thing like that probably makes it cheaper to manufacture, but makes it more expensive to replace. Also, by the looks of it, you have to wait for the filter to become clogged before you replace it, which is less than ideal! Typically the fuel regulator never needs replacing, so having them combined also means you are replacing a perfectly good part just for a new filter which are quite cheap.

An inline fuel filter doesn't need to be replaced any sooner than one of those combined units, it's just preventative maintenance. If you look at a traditional fuel filter it seems to have a larger filtering capacity than the combined one you have. It's possible the injectors are stuffed due to ineffective filtering... Fuel injectors require very pure fuel (in terms of absolutely no solids) due to the action of the internal valve and nozzles, I doubt such a small filter on the regulator will provide the 100 percent filtering required to prevent fuel injector damage. This would probably show up in the resistance due to the solenoid action.

I haven't heard of fuel injectors themselves actually becoming faulty, only the nozzles becoming a little clogged due to carbon deposits from the actual chamber, which is what is represented on fuel system cleaner boxes. Of course, I haven't heard of companies cheapening out to the extent of a combined fuel filter/fuel regulator before either.

Most cars since 2000 have the filter inside the tank, all as one unit. It's *very* expensive to change it out if it has a problem. Mine is a 98 and has the filter in line, frame mounted. It was one of the last of its kind though.